There appears to be a new subspecies of the genre novel in the making: the eco-thriller. We've seen examples of it here and there over the years, a small but interesting group of novels that take up the question of how to care for where we live while we live.

James D. Houston's 1998 novel “The Last Paradise,” in which developers meet up with the forces of a Hawaiian goddess, serves as a good model. So do T.C. Boyle's novels “A Friend of the Earth” and “When the Killing's Done.” And we're getting closer to a purer variety, as in “Flight Behavior,” Barbara Kingsolver's latest novel.

“Zoot-Suit Murders” author Thomas Sanchez's first novel in nearly a decade, “American Tropic,” is a slender, power-packed thriller set in his beloved Key West. It puts him squarely in this group.

Key West, as Noah Sax, a disbarred lawyer with an alcohol problem and a ship he has turned into a pirate radio station just offshore, intones into his microphone at sunrise, “Cayo Hueso, Island of Bones — that was the name the early Spanish explorers gave the place ... last American island, end of the road at the famous sign, MILE MARKER ZERO.” It's a small town, where, at least in Sanchez's novel, people are married to each other's friends, and the bartender at your favorite hellhole watering place is the soon-to-be-ex-wife of the pirate radio guy.

However, there's worse than piracy, radio or otherwise, going on as the book opens. Someone has revived the ghastly figure of Bizango, a serial murderer in a skeleton suit. He first appeared in Sanchez's 1990 Key West novel “Mile Zero,” terrorizing the island until hunted down and killed.

This new Bizango has taken it upon himself to murder those who would despoil the environment. Mainly with a spear gun, the bizarre executioner skewers and crucifies some partners in a huge Keys development, the captain of a cruise ship and a callous female fishing boat captain named Pat who bludgeons hundred-of-years-old sea turtles to death and sells their body parts to Chinese fetishists.

A police detective named Luz, a gay Cuban American mother of two girls, one of whom is deathly ill, takes on the case with her own particular sense of vengeance. (It was her father, himself a Key West cop, who brought down the original Bizango.)

But as violent as these murders may be, and Sanchez makes them as bizarre as Bizango himself, nothing jars like Captain Pat slicing off the dorsal fin of a live dolphin to use as bait to catch a sea turtle (they “think it's drifting squid,” she says to her first mate), hooking and netting a turtle, and then murdering it with a hammer that “penetrates deep into the turtle's skull with a bone-shattering blow.”

The mate throws up. I nearly did. And because of such violence, this neatly plotted book with an exotic setting rises to the level of ferocious dramatic polemic against some of the worst crimes against nature — and, by extension, humanity.